Differential transformer type magnetic sensor and image forming apparatus

An image forming apparatus, comprising a differential transformer type magnetic sensor, wherein

• the differential transformer type magnetic sensor includes:
• a first coil layer including a detection coil formed of a planospiral first wire located on a plane and a first drive coil formed of a planospiral second wire running in parallel to the first wire on the same plane as the first wire;
• a second coil layer including a reference coil formed of a planospiral third wire located on a plane and a second drive coil formed of a planospiral fourth wire running in parallel to the third wire on the same plane as the third wire;
• and
• a first insulating layer arranged between the first coil layer and the second coil layer,
• wherein the first drive coil and the second drive coil are electrically connected together so that a direction of drive current flowing in the first drive coil is the same as a direction of drive current flowing in the second drive coil, and
• the detection coil and the reference coil are electrically connected together so that a direction of induced current flowing in the detection coil is reverse to a direction of induced current flowing in the reference coil.